Five Things you Should Know about Controlled Atmosphere Furnaces


controlled atmosphere furnaces

Controlled atmosphere front load furnace

  1. There are many suppliers of vertical and horizontal tube furnaces, but few suppliers of front load, bottom load, and top hat furnaces specially designed for processing in inert atmospheres. To do so, the furnace must be sealed: the element ports, thermocouple ports, and door access. Gas inlets will allow purging in any furnace, but to operate in other atmospheres the room air in the furnace must be displaced by the desired gas or gas mixture. Gases may include argon, nitrogen, oxygen, and hydrogen mixtures.
  2. Tube furnaces are ideal for applications requiring relatively small workspaces and perhaps features such as multiple zones, independently controlled. Alumina tubes are required for high temperature operation, but they are subject to thermal shock. The smaller the diameter of the process tube, the better. Deltech manufactures tube furnaces for operating temperatures up to 2000 degrees centigrade. In addition to vertical and horizontal tube models, we offer a bottom loading vertical tube and combination units that allow the tube to be placed either vertically or horizontally. Water cooled end caps and gas mixing systems are optional.
  3. Tube furnaces designed for operation at 3600 degrees fahrenheit require use of a zirconia tube.
  4. Deltech sealed atmosphere furnaces are called “atmosphere envelopes”. They are available in bottom load, front load, and top hat models, in most any size and configuration that the application requires. They operate at pressures up to .022 atmosphere. Vacuum assisted evacuation is optional, allowing the user to remove the room air before backfilling with the desired gases.
  5. Element limitations reduce the recommended operating temperatures in furnaces using molydisilicide heating elements. In inert atmospheres, there is a 100 degrees centigrade reduction. In even 5% hydrogen mixtures, it is much lower. The use of moist hydrogen improves on this by 300 degrees centigrade.




  • Hao Gan, Ph.D. says:

    I am looking for a high temperature furnace to melt glass around 1250C in reducing atmosphere (CO+CO2). I will place a 600ml Pt/Au crucible (about 4inch diameter and 4 inch tall) inside. Preferably, a bottom loading furnace. I will consider other configurations too.

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